Potential for female hemophiliac

[RonnieLee88]

I did a search and couldn't find any threads on this, but I'd be amazed if I were the first person to think of it. If this has already been discussed, moderators may feel free to delete this thread. Also, feel free to move it if necessary; I didn't know where else to put it.

This is just something I thought of in my Russian history class the other day, and is strictly a "what if" scenario. It probably wouldn't have been plausible even if the Romanov family hadn't been assassinated.

If Alexei had lived into manhood and gotten married, it would have been impossible for any of his potential daughters not to be affected in some way by hemophilia. Since girls get one X gene from each parent and the only X Alexei could have passed along would have been infected, then any and all of his (theoretical) daughters would have at least been carriers. However, if he had married a woman who was a carrier, then there would have been the potential for their daughter to inherit a defective X gene from each parent, thus making Alexei the father of a rare female hemophiliac.

Am I correct in thinking this? What I'm asking is, could it really have worked out this way? I don't claim to be any kind of expert in either genetics or hemophilia. It was just a possibility that occurred to me and I wanted to know what other people thought.

[Forum Admin]

his daughters would have been carriers.  "IF" he married a female carrier, their daughters would have a one in four chance of having hemophilia. (i believe, not sure of the specific odds)

[Kalafrana]

I agree with Forum Admin. Any sons Alexei had would be unaffected, unless their mother was a carrier, but any daughter would be a carrier. The example is the children of Leopold of Albany. His daughter Alice was a carrier and had a haemophiliac son (though her daughter seems not to have been a carrier), while his son, Charles Edward, was unaffected.

If Alexei married a carrier, their daughters would certainly be carriers, and there is the possibility of one or more being haemophiliac herself (quite apart from the 'ordinary' risk of sons inheriting the haemophilia gene from their mother). I think Nicholas and Alexandra would have had to rule out all descendants of Queen Victoria while finding a bride for Alexei!

Ann

[windemere]

Due to advances in medical treatment for hemophilia, more hemophiliac men are surviving to reproductive age, and having children. Also, probably as a result of this, although hemophilia in women remains very rare, it is more common now than it was in the past. (There is a greater chance of a woman now inheriting an affected X from both her carrier mother, and from her affected father, resulting in two affected XX chromosomes ( a woman with hemophilia ). However, just as in men, due to advances in medical treatment, hemophilia in women is now manageable. A hemophiliac women, with good medical care, can even give birth herself. Since she has 2 affected X chromosomes, her sons will automatically have hemophilia, and her daughters will automatically be carriers. Genetic counselling would be recommended.

Incidentally, hemophilia can also arise as a spontaneous mutation in the X chromosome. It is then passed on to future generations, and becomes hereditary. This is probably how it originated in Queen Victoria, as there was no previous history of hemophilia in her forebears. The mutation isn't common, but is more likely to occur in  a birth in advanced maternal age. I believe Victoria's mother gave birth to Victoria at a somewhat advanced age, and one of Victoria's X chromosomes must have been a spontaneous mutation.